Please provide full logs: grab-logs -A
Update: It looks like it might be a kernel-related issue
I had previously used
rpi-updateto update the installed kernel (to 4.14.90-v7+). When I revert back to the stock kernel (4.14.79-v7+), things work as documented.
FYI, the previous OSMC kernel was 4.14.78-4.
Also see:
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=224931&start=25#p1396409
Unfortunately the hostapd 2.4 shipped with Raspbian Stretch failed with Linux 4.18 and newer
It seems that you need version 2.7, which ships with Debian buster.